Follow Fast Company

Most of the energy in that expensive gas you put in your car is wasted as heat, but new shocks could take some of that wasted energy and put it back into the car, giving you way more bang for the burn.

From an energy perspective, your car is really just a heat machine that happens to move. Only 10 to 16% of the fuel energy that you burn moves the car forward (by overcoming air drag and road resistance), while the rest is dissipated on its way to the drive train. But engineers have been looking to get more bang for their burn since cars rolled off the assembly line. One overlooked source of power has been the suspension system—until now. Conventional shock absorbers dissipate energy through a combination of coiled metal springs and hydraulic dampers. Several engineering teams are now developing what is essentially a miniature power generator for wheels that will convert vibrations into useful energy, as well as a smooth ride.

It works by forcing fluid through a hollow circuit that is coupled to a hydraulic motor and electric generator. Microprocessors optimize the flow of fluid, pumped by bumps in the road, for both ride and power. If deployed on a mass scale (and field tests hold up) fuel efficiency gains could be as high as 6% with longer driving range for hybrid-electrics. Since the technology basically works on anything that moves, the applications are beginning to make their way into an array of other fields: wave-energy devices, ocean sensor systems, building and bridge damping, and vibration-reduction for industrial machines.

The new shocks were a difficult engineering challenge, says David Diamond vice president of business development at Levant Power, which plans to release its first commercial system, GenShock, by 2012 (military vehicles are already testing the system). "The key was harvesting small amplitude, (relatively) high frequency oscillations and taking advantage of the mechanical gain that an electro-hydraulic system would provide," wrote Diamond by email. "There were many dead ends and tough learnings that contributed to the latest highly efficient and durable models."

Levant is not alone. A research group out of Stony Brook University took a different approach, designing what it calls "linear and rotational electromagnetic energy harvesters" that will replace traditional shock absorbers. Instead of turning a hydraulic motor, as GenShock does, it relies on oscillating magnets and metal coils to generate an electrical current. The researchers claim they can boost fuel efficiency 1 to 4% in conventional cars and up to 8% for hybrid vehicles.

Whatever technology prevails, the power motion seems destined for the big time. As efficiency premiums grow more valuable, technologies squeezing every last electron out of systems designed during an era of cheap and abundant energy will become ever more prized. Our cars, subject to proposed fuel economy standards of 56 miles per gallon by 2025, are no exception.